Re: What are Shells?! Can someone please explain them to me?

"Shells" are basically the "shell" or shape of a building. They're unfurnished. They may or may not have any interior walls or a roof. For a shell challenge, they're often just unpainted exteroir walls and nothing else. For non-challenge shells, they'll probably have roof, landscaping, windows & doors, and exterior paint/decorations.

Generally a "shell challenge" is when someone has made some sort of weird/challenging shape to be the outside walls, and the challenge is to use that to make a complete build, without either expanding or deleting that exterior at all. They share the shell to the gallery, and people download it and then share their completed builds tagged to that challenge.

Other times people will create and share shells just because that way you get a house that looks really nice without having to fuss with it, but you still get to furnish it however you want. These are the ones with finished exteriors and landscaping.